Low volume on less efficient speakers, recommendations please [solved]

[ebag4]

I am currently running a Stereomour, I love it's sound.  My previous speakers were 97dB efficient, my new speakers are a little less efficient at 94dB.  The amp is high passed at about 175Hz, the speakers are an 8 ohm load and easy to drive (dual 12" servo woofers per side cover to 200Hz, have their own amp).  The DAC that is feeding the Tortuga LDR has these specs:

450mW, 2.65vrms (Geek Out 450)
â—¾Output impedance: 0.47 ohms (headphones) and 4.7 ohms (line out)

My issue is that on a small portion of music the level is maxed out with the Tortuga LDR volume control pegged.  It still sounds great but I don't believe I am getting everything these speakers offer.  They sound great on 90% of my music at levels I typically listen at, but every once in a while they need a bit more.

I have tried a small digital amp (Yuang Jing Blue Black board?) that puts out about 15 watts, it sounded brittle compared to the 2A3 although the additional power offered what is needed.  Ideally there would be a way to get more volume out of my current amp.

With most of my music I get sufficient volume and more, my question is this; since I can play much of my music with plenty of volume does this point to a gain issue because I have some music that doesn't play at sufficient volume?  Does it make sense to put a pre-amp in front of the Stereomour to get more gain or would this be redundant, would it lead to more noise?

I typically believe that less is more in audio, so if I had an option that allowed the Stereomour to drive the speakers with sufficient volume that would be my first choice.  However if adding a pre-amp is what is needed I will do that to keep the Stereomour in the chain.

Recommendations are appreciated.

Thanks,
Ed

[fullheadofnothing]

Have you tried removing the LDR from your system? An extra volume control in there is going to cost you some gain. Stereomour gives full output at .4V, so it sounds like your DAC should drive it pretty hot.

Of course, you are talking about lowering the efficiency of your speakers, going from above the recommended 96dB threshold to below it. The problem with low-efficiency with low-power isn't that it doesn't work, it's that it may not work to your liking...

[Grainger49]

You might benefit from a Quickie or Smash to increase the signal to the needed 0.4V level.  If you can borrow a preamp from a friend to test this you might be pleasantly surprised.

[Paul Birkeland]

The Tortuga LDR says in its specifications that it will go to 0dB attenuation.  I think Josh's suggestion of verifying this is a very important step.

The next would be to make absolutely sure that no level controls in the digital realm are turned down.  You could download a 60Hz test tone, play it through the DAC, then measure the AC voltage present at the RCA output jacks. 

-PB

[ebag4]

Thanks for the replies guys. 

To answer your question, yes, I have removed the LDR and used the digital volume control built into Audirvana, I still had to max out the digital volume control on some songs.

I do have an old Outlaw 950 preamp that I will pull out of the closet and try, hopefully this weekend.

I want to reiterate, the amp has plenty of volume for most of the music I play, the issue is some songs seem to be recorded at lower levels.  I have read over 102dB on my dB meter with some music using this system, much louder than I would typically listen.

Thanks again for any insight you can offer. 

Best,
Ed

[Grainger49]

In most cases a preamp is used to attenuate the incoming source.  But then there are a few cases that need amplification. 

That is a good reason to have an active stage where you are in control.

[ebag4]

I was able to insert my Integra DTC-9.8 pre-pro into my 2 channel system today and take some dB measurements. 

With the Integra set up flat (0 dB on all settings) and the volume at 0dB the readings were very similar to the maximum volume on my Tortuga LDR given the same material. 

For most material 2-3 +dB is the loudest I would ever listen.  For one of the tracks recorded at the lowest level a +10dB setting is the loudest I could ever listen.

I am thinking I need to add a preamp.  The Integra sounds good and adds what I perceive as drive, especially in the bass frequencies, but given the same volumes the LDR is cleaner IMO.

So I am looking for recommendations.  If a preamp, which one.  I could go with The Smash, would it hold the Stereomour back?  If pressed I could go with the BeePree.  Not sure if I will like the 300b, I have never heard one.

Bottom line is I am happy I can stay with my Stereomour, although I would listen to argument recommending forgoing the preamp and going with a 300b amp instead.

Thanks,
Ed

[Paul Joppa]

Our 300B power amp needs more input than the Stereomour, so you would definitely need a preamp with it. But if your loudest listening (using the Integra) does not produce clipping distortion then you don't need more power.

[ebag4]

Thanks Paul.  The Stereomour is high passed at about 175 Hz, it is my understanding that it is less likely to clip when not being asked to reproduce bass frequencies.  I am not certain I know what clipping sounds like, but am I correct to understand that if I can keep turning the volume up (on the Integra in this case) and the volume continues to increase when reading the SPLs on a dB meter that it is unlikely I am clipping?  I am able to do that all the way to +18 dB on the Intregra, although I don't think I could ever use it beyond +10, it gets too loud.

One other question, does a preamp with 10dB gain to equate to +10dB on the Integra volume control?  It seems it should however I am not certain what the relationship is between preamp gain and volume control settings.

Thanks,
Ed

[Paul Joppa]

Clipping in SETs is a lot more subtle than solid-state amps. I hear it as distortion on signal peaks, just a little less "life" to the sound.

With well-recorded music, the instantaneous peaks are 10-20dB above level of most of the energy, so you can easily get the music louder while well into clipping. With high-feedback amps, the clipping generates a lit of scratchy high frequency noise which is absent in SETs - it's a different sound. Once I learned to recognize it, I can no longer put up with it, but many others are just not bothered by it. That's why I suggested you try it with the preamp, to see what you hear and how much it bothers your ears.

[ebag4]

I thought I would follow up, I tried your recommendation Paul.  I tried a small buffer/preamp (6dB gain as pre), an inexpensive unit but well reviewed unit, it doesn't seem to add much of its own sound so I am happy.  I have run it as a pre with a Geek Out DAC, and now as a zero gain buffer with an Auralic Vega DAC.  Both solutions gave satisfactory drive and volume with my current speakers (94dB).  If it is clipping I am not hearing it as distortion, this is the best sound I have heard, I am very happy I was able to use my Stereomour with these speakers.

I purchased a class T amp (30 watts) to try with the speakers and it sounded very good, but when I hooked the Stereomour back up there was just no comparison, I love this amp.

Thanks for the recommendation Paul, good advice.

[Paul Joppa]

(nt)